The present invention relates to an electromagnetic shielding plate having electromagnetic shielding function, and also to an electromagnetic structure composed of the electromagnetic shielding plates which are connected to each other in two dimensions or in three dimensions.
In order to transmit a large volume of electronic information with development of information and communication societies, signals having high densities and high frequencies have become popular in electronic apparatuses. On the other hand, however, there has frequently occurred such a trouble that electromagnetic wave arising from the electronic apparatuses may generate noise and cause radio disturbance in a peripheral equipment, and it has been an urgent necessity to take countermeasures against the trouble.
As the electromagnetic shielding measures, it has been a general practice that a filter circuit such as a high frequency filter is provided in a circuit-of the electronic apparatus itself. Moreover, the electromagnetic shielding measures are also adopted in a box containing this electronic apparatus or in a structure such as an architecture. For example, walls, a floor and a ceiling of an electromagnetic shielding room 1 as shown in FIG. 4 are composed of electromagnetic shielding plates 2.
However, as shown in an enlarged scale in FIG. 5, the related electromagnetic shielding plate 2 has been generally composed of electromagnetic shielding material 4 in a form of a thin metal plate, a metal impregnated plastic sheet, an electrically conductive coating film or the like which has been attached to a surface of a substrate 3 made of wood, gypsum, stone or the like. This electromagnetic shielding plate 2 has inevitably become larger in weight, since the substrate 3 has been made of heavy material. For this reason, requirement for enhancing strength of the base and skeleton of the structure has arisen, and there has occurred such a problem that the cost will be inevitably increased.
Moreover, nowadays, the electromagnetic shielding measures are required to be taken in a vehicle, because various electronic apparatuses having high frequency motions are mounted on the motor car in order to give functions of electronic control and communication. In case where these electronic apparatuses are contained inside the same electromagnetic shielding plates 2 as described above, weight of a vehicle body will be increased, which may incur a decrease of fuel efficiency.
In the related electromagnetic shielding plate 2, the substrate 3 and the electromagnetic shielding material 4 must be bonded to each other. This will lead to such a problem that production and/or installation will be complicated.
The present invention has been made in order to solve the above described problems, and an object of the present invention is to provide an electromagnetic shielding plate which can be obtained by a simple process, made light, and has high electromagnetic shielding effects, and also to provide an electromagnetic shielding structure composed of the described electromagnetic shielding plates.
In order to attain the above described object, there is provided, according to the present invention, an electromagnetic shielding plate comprising hollow particle dispersed composite material which includes a metal matrix containing therein hollow particles formed of inorganic compound.
The electromagnetic shielding plate material having such a composition can be remarkably made light as compared with the conventional substrate, and its electromagnetic shielding property can be also enhanced. In addition, there is no need of a step of bonding the substrate and the electromagnetic shielding material as in the prior art.
Further, there is provided according to the present invention, an electromagnetic shielding structure which includes a plurality of the above described electromagnetic shielding plates which are connected to each other in two dimensions or in three dimensions.
This electromagnetic shielding structure such as an electromagnetic shielding room or box, for example, is composed of the light weight electromagnetic shielding plates. Accordingly, its skeleton need not be reinforced, and even though the structure is employed to be mounted on a vehicle, a decrease of fuel efficiency due to an increase of weight will not be incurred.